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  Subjects -> CHEMISTRY (Total: 775 journals)
    - ANALYTICAL CHEMISTRY (45 journals)
    - CHEMISTRY (539 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (24 journals)
    - INORGANIC CHEMISTRY (40 journals)
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    - PHYSICAL CHEMISTRY (64 journals)

ANALYTICAL CHEMISTRY (45 journals)

Accounts of Chemical Research     Full-text available via subscription   (Followers: 219)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 9)
Acta Analytica     Hybrid Journal   (Followers: 6)
Advances in Analytical Chemistry     Open Access   (Followers: 19)
American Journal of Analytical Chemistry     Open Access   (Followers: 26)
Analytica Chimica Acta     Hybrid Journal   (Followers: 32)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 26)
Analytical Chemistry     Full-text available via subscription   (Followers: 314)
Analytical Chemistry Insights     Open Access   (Followers: 17)
Analytical Letters     Hybrid Journal   (Followers: 9)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 10)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Chinese Journal of Analytical Chemistry     Full-text available via subscription   (Followers: 3)
Combinatorial Chemistry - an Online Journal     Open Access   (Followers: 2)
Comprehensive Analytical Chemistry     Full-text available via subscription   (Followers: 5)
Critical Reviews in Analytical Chemistry     Hybrid Journal   (Followers: 25)
Current Analytical Chemistry     Hybrid Journal   (Followers: 6)
Drug Testing and Analysis     Hybrid Journal   (Followers: 4)
Electroanalysis     Hybrid Journal   (Followers: 3)
Field Analytical Chemistry and Technology     Hybrid Journal   (Followers: 5)
Handbook of Analytical Separations     Full-text available via subscription   (Followers: 1)
Handbook of Thermal Analysis and Calorimetry     Full-text available via subscription  
International Journal of Analytical Chemistry     Open Access   (Followers: 20)
International Journal of Chemical and Analytical Science     Full-text available via subscription   (Followers: 3)
International Journal of Environmental Analytical Chemistry     Hybrid Journal   (Followers: 5)
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 4)
ISRN Analytical Chemistry     Open Access   (Followers: 16)
ISRN Chromatography     Open Access   (Followers: 2)
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 5)
Journal of Analytical Atomic Spectrometry     Full-text available via subscription   (Followers: 8)
Journal of Analytical Chemistry     Hybrid Journal   (Followers: 15)
Journal of Electroanalytical Chemistry     Hybrid Journal   (Followers: 4)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 2)
Journal of Radioanalytical and Nuclear Chemistry     Hybrid Journal   (Followers: 3)
Journal of Thermal Analysis and Calorimetry     Hybrid Journal   (Followers: 19)
Main Group Metal Chemistry     Full-text available via subscription   (Followers: 1)
Microchemical Journal     Hybrid Journal   (Followers: 3)
Phytochemical Analysis     Hybrid Journal   (Followers: 1)
Polish Journal of Chemical Technology     Open Access   (Followers: 2)
Reviews in Analytical Chemistry     Full-text available via subscription   (Followers: 8)
Surface and Interface Analysis     Hybrid Journal   (Followers: 14)
Techniques and Instrumentation in Analytical Chemistry     Full-text available via subscription   (Followers: 7)
TrAC Trends in Analytical Chemistry     Full-text available via subscription   (Followers: 21)
Trends in Environmental Analytical Chemistry     Hybrid Journal   (Followers: 1)
Vibrational Spectroscopy     Hybrid Journal   (Followers: 8)
Journal Cover Journal of Analytical Chemistry
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1608-3199 - ISSN (Online) 1061-9348
     Published by Springer-Verlag Homepage  [2209 journals]   [SJR: 0.322]   [H-I: 17]
  • Electrochemically modified semiconductor gallium arsenide electrodes for
           the argentometric titration of chlorides with silver nitrate in natural
           samples
    • Abstract: Abstract An electrochemical method is proposed for the modification of the surface of semiconductor gallium arsenide sensors. The electrochemical modification of the surface of GaAs-electrodes leads to the improvement of their electrochemical characteristics: an increase in the slope of the electrode function, a decrease in response time, and the extension of the concentration range. Potentiometric titration using unmodified and modified GaAs-electrodes for the determination of chlorides with silver nitrate in soil has been performed. The application of the modified sensors ensures the detection of the titration end-point with a higher accuracy.
      PubDate: 2014-11-01
       
  • Suspended droplet solvent microextraction-flame atomic absorption
           spectrometry (SDSME-FAAS) determination of trace amounts of copper in
           river and sea water samples
    • Abstract: Abstract A simple and sensitive suspended droplet solvent microextraction (SDSME) method is proposed for the preconcentration and determination of copper by flame atomic absorption spectrometry (FAAS). The analytical procedure is based upon the formation of a complex between Cu(II) and 1-phenyl-1,2-propandione-2-oxime-thiosemicarbazone (PPDOT) as a complexing agent. After extraction of the complex by 1-octanol, copper concentration in the solvent drop was determined by FAAS. The effect of different parameters such as pH, PPDOT concentration, kind of buffer, kind and volume of organic solvent, volume of aqueous phase, extraction time, stirring rate of sample solution, temperature, and ionic strength were investigated. The effect of foreign ions on the determination was also studied. Under the optimized chemical and instrumental conditions, a linear calibration curve was achieved in the range of 0.0050–0.26 mg/L, with the limit of detection of 3 μg/L and the enrichment factor of 52.6. This method can be applied successfully to the determination of copper in water samples.
      PubDate: 2014-11-01
       
  • Migration study of zinc dibutyldithiocarbamate in eye drops solutions
    • Abstract: Abstract The potential deleterious effects of extractables/leachables in pharmaceutical products and the need to preserve product safety throughout its shelf life have led the three major pharmacopoeias (USP, EP, JP) to require extractable and toxicity testing of container/closure systems. To that, a HPLC/UV method was developed and validated for the detection of zinc dibutyl dithiocarbamate (ZDBC) as potential extractable from pharmaceutical container closure system of eye drops solutions. The method consists of direct extraction of the analyte with chloroform; the lower layer was evaporated to dryness and further reconstituted with acetonitrile. The chromatographic separation was performed on a Nova-Pak C18 column using as mobile phase a mixture of acetonitrile:water. Calibration curves were linear and relative standard deviation was sufficient. Detection limit of ZDBC was found to be 0.015 μg/mL. The HPLC method was further applied in seven currently marketed eye drops solutions, confirming its applicability for monitoring dithiocarbamates migration from container closure systems into the eye drops solutions.
      PubDate: 2014-11-01
       
  • The determination of GC-MS relative molar responses of benzene and
           biphenyl derivatives
    • Abstract: Abstract The dependence of relative response factors on the carbon and chlorine atom number related to naphthalene has been investigated by using gas chromatography-mass spectrometry (GC-MS). The main goal of these investigations is to find some relationship between the GC-MS signal (peak area) and the test molecule chemical structure. By means of the knowledge of correlations of relative molar response, the quantitative analysis passes into easier and fewer reference materials are needed to investigate a sample having lot of component, because the sensitivities can be determined from the correlations studied in this paper. This is very important in daily analytical tasks, particularly for impurity profiling studies. Relative responses of some polychlorinated benzenes, polychlorinated biphenyls and n-alkylbenzenes are compared in the experiments. Linear correlation is found between the molecular structures of n-alkylbenzenes, i.e. the carbon atom number, and relative molar response. Relative molar responses of polychlorinated biphenyls also provided linear correlation taken as a function of chlorine atom number. Under given conditions, the increments of CH2 unit and chlorine atom number to the relative molar responses are 0.221 and 0.198, respectively. However, relative responses of polychlorinated benzenes showed diversity plotted against chlorine atom number, and their isomer compounds also gave various results according to the first ionization energy. The measurement conditions can influence the relative responses. The low injector temperature, the interface and the ion source temperature affected relative responses of high volatile compounds. However, when the parameters are kept under control, the results can become accurate and reproducible.
      PubDate: 2014-11-01
       
  • Sorption-catalytic determination of histamine and lysine after planar
           chromatography using surfactants
    • Abstract: Abstract The effect of ionic surfactants on the separation characteristics of histamine and lysine in model mixtures has been studied by planar chromatography. It has been demonstrated that the impregnation of paper in paper chromatography and the modification of the mobile phase with solutions of sodium n-dodecyl sulfate in thin-layer chromatography improve the selectivity of separation. Use of n-dodecyl sulfate made possible an increase in selectivity and, in some cases, sensitivity of sorption-catalytic determination. A combination of planar chromatography with the subsequent sorption-catalytic determination directly on the support made us possible to develop methods for determining histamine and lysine in the concentration range 1 × 10−12−5 × 10−11 and 1 × 10−7−1 × 10−5 M, respectively. The developed methods have been used to determine histamine in human saliva and lysine in blood plasma and pharmaceutical products.
      PubDate: 2014-11-01
       
  • Characteristic variations of gas-chromatographic retention indices for
           phases of variable composition
    • Abstract: Abstract On an example of mixtures of dinonyl phthalate and 2,2′-bis-(2-cyanoethoxy)diethyl ether, it was shown that the dependence of gas-chromatographic retention indices (RIs) on the composition (α) of mixed stationary phases can be both linear and with various abnormalities. These features of the dependence of RI-α can be explained by the existence of areas of homogeneity and disintegration of mixed phases. Another reason for the nonlinearity of the dependence RI-α is that the components of phases of variable composition are expressed in mole fractions, which is typical for polymethylphenylsiloxanes, widely used in contemporary gas chromatography. It is shown that the expression of composition in mass fractions enables the approximation of these dependencies in the homogeneity regions by linear regression equations with sufficient accuracy.
      PubDate: 2014-11-01
       
  • Sequential determination of nickel(II) and zirconium(IV) with
           dimethylglyoxime and arsenazo III after adsoprtion on one substrate disc
    • Abstract: Abstract The possibility of the sequential determination of nickel with dimethylglyoxime and zirconium with arsenazo III from a single aliquot portion using polyacrylonitrile fiber as a solid phase impregnated with a KU-2 cation exchanger is studied. Conditions for the simultaneous adsorption of nickel and zirconium in the dynamic mode from 0.01 M HNO3 are found as along with the ones for their sequential determination on one disc. The calibration functions are linear in the range 5–50 ng/mL, the detection limits for both elements are 2 ng/mL. In their simultaneous presence, the determination of nickel and zirconium is not affected by 10-fold weight amounts of Fe(III), Cu(II), Co(II), Al, Mn(II), Pb, Zn, Cd, Cr(VI), Mo(VI), and V(V). A method is proposed for determining nickel and zirconium from a single aliquot portion on a single substrate disc at their ratios from 1: 1 to a 5-fold excess of each element.
      PubDate: 2014-11-01
       
  • Metrological characteristics of lead determination in rare earth
           phosphates by electron probe microanalysis
    • Abstract: Abstract An equation for the calculation of the detection limit c lim is presented. Relations for the limit of detection c lim, limit of determination c min, and relative error V of analyte determination are derived. The performance characteristics of lead determination in rare earth phosphates on a JXA-8100 microanalyzer are found. Under the typical conditions of the determination of monazite age (15 kV, probe current of 250 nA, count time in the positions of the line and background 400 s each) c min using the 2σ-criterion is 0.006 wt % for an ordinary spectrometer and 0.004 wt % for a high-aperture one. In the simultaneous registration of lead by the scheme ”two ordinary plus one high-aperture channel,” c min is reduced to 0.003%. For c min = 0.006%, the acceptable error of age estimates V of 1–3 relative percent is attained at c lim = 0.3-0.08%, respectively. As was found, the lowest capacity of microanalyzers for geochronology needs is 0.02–0.03% of PbO. Equations of constraints for the performance characteristics of methods ensure the revelation of the necessary conditions of analysis and compliance with them.
      PubDate: 2014-11-01
       
  • Detection of acrylamide vapors by ion mobility increment spectrometry at
           reduced pressures
    • Abstract: Abstract A possibility of the detection of acrylamide from aqueous solutions at reduced pressures using an ion mobility increment spectrometer-mass spectrometer has been studied. An increase in instrumental resolution for ions containing acrylamide and obtained by coevaporation from an aqueous matrix at reduced pressures from 1 to 0.4 atm has been demonstrated.
      PubDate: 2014-11-01
       
  • Extraction of chromium(VI) with blue tetrazolium chloride and
           tetranitrotetrazolium blue chloride
    • Abstract: Abstract The optimum conditions for extraction of microquantities of chromium(VI) as an ion-association complex with blue tetrazolium chloride (BTC) and tetranitrotetrazolium blue chloride (TNBT) has been determined. The extracted species was a 1: 2 of the BTC and TNBT cation and the chlorochromate anion. Beer’s law was obeyed in the range of 0.04–0.8 μg/mL Cr(VI) for BTC and 0.1–1.6 μg/mL Cr(VI) for TNBT. The molar absorptivities were ɛ255 = 7.77 × 104 L/(mol cm) (for BTC) and ɛ275 = 2.04 × 104 L/(mol cm) (for TNBT). Sandell’s sensitivity of the systems were found to be 6.69 × 10−4 μg/cm2 (for BTC) and 2.55 × 10−3 μg/cm2 (for TNBT). Limit of detection (LOD) is 8.55 ng/mL and limit of quantitation (LOQ) is 0.028 μg/mL Cr(VI) for BTC. For TNBT, LOD is 0.031 μg/mL and LOQ is 0.103 μg/mL. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase have been determined. A sensitive method for determination of trace of chromium(VI) in plants has been developed.
      PubDate: 2014-11-01
       
  • Possibilities of NMR spectrometry in determining trace components of
           mixtures
    • Abstract: Abstract The possibility of using nuclear magnetic resonance (NMR) spectrometry for the determination of trace components in mixtures in the concentration range 1 × 10−5–5 × 10−4 M is shown. The conditions of NMR experiments at which the measurement error attains a minimum are standardized and the precision of NMR spectrometry in determining trace components of mixtures within the analytical range is estimated.
      PubDate: 2014-11-01
       
  • A new sensitive method for the determination of trace mercury by
           differential pulse polarography: Application to raw salt sample
    • Abstract: Abstract A new indirect differential pulse polarographic (DPP) method is established for the trace determination of mercury(II). Because of its toxic effects on human health, trace determination of mercury is very important. An indirect method had to be used since no polarographic peak is observed in its direct determination. According to the standard potentials, the reaction between Sn(II) and Hg(II) was found suitable. The peak of Sn(II) at about −0.40 V is sharp, high and very reproducible, which enables the determination of low concentrations of Hg(II). For this purpose, to a known amount of Sn(II) present in the polarographic cell (acetic acid, HAc, pH 1–2), the unknown Hg(II) sample is added and the quantitative reaction takes place directly in the cell. The Hg(II) concentration is calculated simply from the decrease of the Sn(II) peak. The limit of detection (LOD) was found as 2 × 10−7 M for S/N = 3. Interferences of some common cations, such as Fe, Cd, Cu, Zn and Pb and anions have been investigated. Only Pb had an overlapping peak with Sn(II). This peak overlap was eliminated simply by working at pH 2 (HAc electrolyte), because of the shift of the Pb peak in the Ac complex to −0.7 V. This method was successfully applied to synthetic samples and raw salt sample taken from a salt lake in Turkey.
      PubDate: 2014-11-01
       
  • About the limit of detection in X-ray fluorescence analysis
    • Abstract: Abstract Blank experiment in X-ray fluorescence analysis is actually a measurement of the background at the analytical line of an element to be determined. Numerous factors affecting the appearance and registration of the background signal are responsible for its normal distribution. In this work, the possibility of using real samples with low analyte concentrations as blank samples is substantiated. A criterion for the assessment of the correctness of different equations for calculating the limit of detection is proposed. An expression for the calculation of the limit of detection using a one-sided confidence interval of the distribution of analytical signal is derived. An algorithm for the assessment of the limit of detection is proposed.
      PubDate: 2014-11-01
       
  • Monitoring analytical measurements in presence of two component
           measurement error
    • Abstract: Abstract Control charts are increasingly adopted by laboratories for effective monitoring of analytical processes. Analytical methods are mostly subject to two types of measurement errors, i—additive and ii—multiplicative, or proportional, error. These errors have been combined in a single model, namely the two component error model (TCME) proposed by [1]. In this study we present a comparison among the performance of three widely used location control charts, i.e. Shewhart, CUSUM and EWMA charts in presence of TCME model. This study will help quality practitioners to choose an efficient chart for the monitoring of analytical measurements.
      PubDate: 2014-11-01
       
  • Erratum to: “Evolution of new narcotic substances and methods of
           their determination”
    • PubDate: 2014-11-01
       
  • Liquid membrane potentiometric sensor for determination of Fe 3+ ion
    • Abstract: Abstract Solution studies showed a selective interaction between the new synthesized ionophore, 2-[(thiophen-2-yl)methyleneamino]isoindoline-1,3-dione (TMID) and Fe(III) ion. Therefore, TMID was used as an iron selective ion-carrier in a plasticized liquid membrane sensor. The linear response range of the proposed electrode was 1.0 × 10−6–1.0 × 10−2 M. The Nernstian slope of 20.1 ± 0.3 mV/decade, and a detection limit of 5 × 10−7 M was obtained. The sensor could be used in the pH range of 2.3–4.8, and the response time was about 10 s. The lifetime of the electrode was at least 7 weeks. The sensor accuracy was investigated in two ways: (i) with the potentiometric titration of a Fe3+ solution with EDTA and (ii) with Fe(III) monitoring in some cationic mixtures. Finally, the newly fabricated electrode was effectively applied as an indicator electrode for the direct Fe3+ determination in real samples.
      PubDate: 2014-11-01
       
  • Simultaneous spectrophotometric determination of pyrantel pamoate and
           febantel in pharmaceutical preparations using partial least-squares
           regression
    • Abstract: Abstract The multivariate spectroscopic determination of the combination of pyrantel pamoate (PP) and febantel (FB) in pharmaceutical preparations was carried out by partial least-squares regression. The UV absorbance spectra of standard mixtures of PP and FB were measured at concentrations ranging from 5.76–11.52 and 6–12 μg/mL, respectively, in a diluent solution of methanol and acetonitrile. The best model was selected with variable selection (280–320, 380–400 nm), 2 latent variables and mean centered. External validation was performed using 13 different mixtures, which provided prediction errors lower than 1%. The method was validated in accordance with international and Brazilian guidelines. This method was successfully employed to quantify the drug content in two different pharmaceutical formulations (solid — capsules, liquid — oral suspensions) with good prediction capacity. Furthermore, its advantages include the use of simple and accessible reagents and equipment, and a low operating cost.
      PubDate: 2014-10-01
       
  • Evaluation of the antioxidant properties of spices by cyclic voltammetry
    • Abstract: Abstract The individual antioxidants of spices (gallic and rosmarinic acids, capsaicin, thymol, and eugenol) are irreversibly oxidized at 0.88–1.25 V at a glassy carbon electrode in 0.1 M LiClO4 solution in ethanol. Corresponding electrode reactions are proposed. A linear dependence of the oxidation step area on the concentration is observed for all the analytes. The detection limits and the lower limits of quantification vary from 0.57–12 and 1.8–40 μM, respectively. Distinct steps and peaks of oxidation are observed on cyclic voltammograms of the methanolic extracts of spices; the potentials and areas of these peaks depend on the type of spice. The contribution of individual antioxidants to integral responses of spice extracts is evaluated. A method is developed for the voltammetric evaluation of the antioxidant capacity (AOC) of spices based on the oxidation of their antioxidants. The total area of the oxidation steps was selected as a parameter characterizing the antioxidant properties. The AOC of spices was expressed as a weight of gallic acid in milligrams per 1 g of a dry spice. Seventeen different spices were tested. The AOC decreases in the series of clove > juniper berries > nutmeg > cinnamon > rosemary > anise ≥ oregano > black pepper ≥ ginger ≥ basil > turmeric > red pepper ≈ bay leaf ≥ coriander ≈ red sweet pepper > cumin > caraway. A correlation between the AOC obtained by voltammetry and the total AOC, ferric reducing power, antiradical activity, and total content of phenolic compounds and these parameters with each other is found; the correlation coefficients vary in the range 0.8886–0.9615.
      PubDate: 2014-10-01
       
  • Determination of bismuth in pharmaceutical products by resonance light
           scattering using quaternary ammonium salts as molecular probe
    • Abstract: Abstract Resonance light scattering (RLS) of bismuth-iodide-quaternary ammonium salts and their analytical application have been studied. Bismuth can react with a large excess of I− to form [BiI4]− in the presence of Tween-20; [BiI4]− further reacts with quaternary ammonium salts such as tetramethyl ammonium bromide (TMAB), tetrapropyl ammonium bromide (TPAB) and tetrabutyl ammonium bromide (TBAB) to form an ion-association compound. Moreover, the characteristics of RLS spectra of the complexes, the optimum conditions and the influencing factors have been investigated. The method has been applied to determine Bi(III) in pharmaceutical products with satisfactory results which are in agreement with that of atomic absorbance spectrometry (AAS).
      PubDate: 2014-10-01
       
  • Study of forced degradation behavior of idrocilamide and development of
           stability indicating LC method
    • Abstract: Abstract The objective of this study was to report the stability profile of novel muscle relaxant drug idrocilamide (Idr) based on information obtained from forced degradation studies. The drug was subjected to acidic (1 M HCl) and alkaline (1 M NaOH) hydrolysis and oxidative decomposition (50% H2O2). The products formed under different stress conditions were investigated by LC. The LC method was fine tuned using the samples generated from forced degradation studies. Satisfactory resolution between peaks with the shortest possible analysis time was achieved on C18 5 μm column (Luna, Phenomenex, USA), with mobile phase methanol-acetonitrile-water-glacial acetic acid (25: 30: 44: 1, v: v: v: v), pumped at 1 mL/min flow rate. Quantification was achieved at 280 nm based on peak area, using DAD detector. The proposed LC method was utilized to investigate the accelerated oxidative degradation of Idr. Besides, Idr’s degradants were identified using IR and MS, and the possible degradation pathway was outlined. The proposed method was validated, and the forced degradation studies proved the stability indicating power of the method. The method was also applied to analyze commercial samples.
      PubDate: 2014-10-01
       
 
 
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